Generally speaking, antennas radiate and/or receive electromagnetic signals. Antenna design often involves a balancing of parameters, such as, for example, antenna size, antenna gain, bandwidth, and efficiency. Mounting antennas on the exteriors of vehicles is well-known.
An emerging trend involves including antennas (e.g., FM antennas) in the laminated front windshield of a vehicle. Such antennas typically include an electrical wire (e.g., a copper wire, about 80 microns in diameter, or other suitable diameter), which may be embedded in a polymer interlayer (e.g., a polyvinyl butyral (PVB) layer) of the front windshield.
Similar to the techniques used for creating heatable windows, if the wire is to be used for an antenna function, rather than connecting both ends of a wire to the respective bus bars, one end of the wire typically is left free in order to capture an electromagnetic field while serving in its antenna function. The antenna wire is laid out in a particular pattern or at a specific location, with certain tensions being applied thereto, for example, to ensure that it is not visible, only partially visible, or visible in an aesthetically pleasing manner. The tensions also help dispose the wire in a particular pattern (e.g., a straight line generally parallel to an exterior edge of the windshield, etc.). The fixed end of the antenna wire may be fixed to (e.g., soldered to or otherwise electrically connected with) a bus bar. Moreover, the antenna wire itself (e.g., at or proximate to the fixed end thereof) and/or bus bar may be operably connected to a transceiver unit (which may, in turn, be connected to, for example, a radio of the car, a power source such as the battery, etc.) so that the radio within the car is operable.
Unfortunately, embedding antennas in windshields in this and/or a similar manners leads to certain disadvantages. A number of heat treatments are included in the process for making windows in general (e.g., during autoclaving), and in making windshields with antennas in particular. At these high temperatures, the PVB typically used in the laminate becomes much more soft, liquefying to some extent, and sometimes even coming close to being rendered a liquid. During these steps, the antenna wire, which has a free end (the end not soldered to, for example, the bus bar), potentially may move. Also, in addition to or apart from the heat-related steps, mechanical forces and/or tensions are introduced during window manufacturing (including, for example, during rolling, unrolling, application of the PVB, etc.) and some or all of the tensions intended to be applied to the wire may be released. Thus, the likelihood of the antenna wire moving from its precise layout is increased yet further.
The most common distortion is a wave shape, as shown in FIGS. 1-2. In more detail, in FIGS. 1-2, a first glass substrate 2 and a second glass substrate 4 are provided. Initially, these glass substrates 2 and 4 are flat. A heatable coating and/or a low-E coating optionally may be deposited between the glass substrates 2 and 4 via sputtering or the like. The heatable coating may be substantially transparent to visible light and may include a transparent conductive layer of a material such as indium-tin-oxide (ITO) or silver (Ag) or may be a multi-layer coating including one or more conductive layers of ITO, Ag, or the like, that may be separated from one another by dielectric layer(s).
One or more conductive bus bars 9 is/are deposited on the substrate 4. The bus bars 9 may be applied in any suitable manner, and may be provided in any suitable location on the substrate (and over the heatable coating when such a coating is provided). For example, the bus bars 9 may be provided generally at the top and bottom or left and right of the windshield.
After the bus bars have been formed on the substrate 4, the glass substrate 4 and bus bar 9 thereon may be heat treated (e.g., thermally tempered, heat bent, and/or heat strengthened). This heat treatment typically is at temperatures of at least 500 degrees C., and more preferably at least about 600 degrees C. During this heat treatment, in example windshield applications, the glass substrate 4 and bus bars thereon may be bent to the desired curved shape for the desired windshield application. When a heatable coating is optionally used, the bus bars 9 may be in electrical contact with at least one conductive and heatable layer of the heatable coating.
A polymer inclusive laminating interlayer 5 of or including polyvinyl butyral (PVB) or any other suitable polymer-based laminating material is provided so as to laminate glass substrates 2 and 4 to one another as shown in FIG. 1. In the laminating process, which typically involves autoclaving, the two glass substrates 2, 4 with interlayer 5 therebetween are heated to typical laminating temperature(s) to laminate the glass substrates to one another thereby finalizing the electrical connections between the bus bars and external connectors, and also forming the vehicle windshield or other laminated window product.
A single antenna wire 21 is shown within the visible portion of the windshield. The fixed end 17 of the antenna wire 21 is electrically connected to (e.g., soldered to) a bus bar 9 at electrical connection area 15, while the free end 19 at least initially floats, e.g., on/within the PVB layer. Although the antenna wire 21 is laid out using a well-defined pattern (in the case of FIG. 2, a straight line generally parallel to the top edge of the windshield and generally perpendicular to the bus bar 9), after pressures are introduced, the wire is bent and/or distorted at areas 23. Yet, whether the antenna wire will become distorted and the extent of any such distortion(s) often is unpredictable.
The end-customer typically does not accept these distortions or even specify an acceptable tolerance (e.g., does not include a requirement in any technical specification for the amount of distortion allowed). Consequently, a significant number of windows are lost in the production flow. The issue is known to and recognized as problem for window suppliers, automobile manufacturers, wire suppliers, and machine makers.
Thus, it will be appreciated that there is a need in the art to overcome one or more of these and/or other disadvantages. It also will be appreciated that there is a need in the art for techniques for providing better performing antenna wires in vehicle windshields.
One aspect of certain example embodiments of this invention relates to an antenna wire provided in an interlayer of a windshield.
Another aspect of certain example embodiments relates to an antenna wire including a fixed end and a free end, with the fixed end being electrically connected to a component of the windshield or vehicle (e.g., a bus bar, radio transceiver, etc.), and with the free end being mechanically connected to interlayer (e.g., via an adhesive).
Still another aspect of certain example embodiments relates to a visible mechanical connection of the free end of an antenna wire to an interlayer of a windshield that also serves as a decorative component of the windshield.
Still another aspect of certain example embodiments relates to a reduction in distortions of antenna wires embedded in windshields and/or an increase in the ability to cause antenna wires embedded in windshields to more closely respect the patterns in which they are arranged or disposed throughout the windshield manufacturing process.
In certain example embodiments of this invention, a vehicle windshield is provided. First and second substrates are laminated to one another via at least a polymer inclusive interlayer. At least one conductive bus bar is provided between the first and second substrates. At least one antenna wire including a fixed end and a free end are provided, with the fixed end and the free end being disposed at opposing ends of the antenna wire. The at least one antenna wire is electrically connected to the bus bar at the fixed end of said at least one antenna, and the at least one antenna wire is mechanically connected to the interlayer at the free end of said at least one antenna via an adhesive.
In certain example embodiments, a vehicle windshield is provided. First and second glass substrates are laminated to one another via at least a polymer inclusive interlayer. Two conductive bus bars provided between the first and second substrates are arranged substantially linearly proximate to a first edge of the windshield. Two parallel spaced apart antenna wires are substantially perpendicular to the two bus bars, with each said antenna wire including a fixed end and a free end, and with the fixed ends and the free ends being disposed at opposing ends of the respective antenna wires. An enamel layer is disposed around at least a part of a periphery of the windshield. Each said antenna wire is electrically connected at the fixed end thereof to one said bus bar, and each said antenna wire is mechanically connected at the free end thereof to the interlayer via an adhesive tape, the adhesive tape being located behind the enamel.
According to certain example embodiments, a method of making a vehicle windshield is provided. First and second glass substrates are laminated to one another via at least a polymer inclusive interlayer. At least one conductive bus bar is provided between the first and second substrates. At least one antenna wire is provided in the interlayer in a predetermined pattern and/or at a predetermined location with respect to the windshield. The at least one antenna wire is electrically connected at a fixed end thereof to the at least one bus bar. The at least one antenna wire is mechanically connected at a free end thereof to the interlayer via an adhesive so as to reduce distortion of the at least one antenna wire during heat treatment of the windshield or a windshield component and/or during application of pressure to the windshield or a windshield component.
According to certain example embodiments, a vehicle is provided. The vehicle includes a vehicle windshield. First and second substrates are laminated to one another via at least a polymer inclusive interlayer. At least one conductive bus bar is provided between the first and second substrates. At least one antenna wire including a fixed end and a free end are provided, with the fixed end and the free end being disposed at opposing ends of the antenna wire. The at least one antenna wire is electrically connected to the bus bar at the fixed end of said at least one antenna, and the at least one antenna wire is mechanically connected to the interlayer at the free end of said at least one antenna via an adhesive.
It will be appreciated that the various aspects, features, and example embodiments disclosed herein may be used in various combinations to achieve yet further embodiments.